# source: Hydrogen Analysis Resource Center /
#        NIST Reference Fluid Thermodynamic and Transport Properties Database (REFPROP): Version 8.0
#        http://www.nist.gov/srd/nist23.htm
# calulated as der_comp = (K(100 bar, temperature)-1)/100 bar
# temperature in Kelvin, derivative of compressibility factor Z in 1/bar
# 273.15 0.000637
# 298.15 0.000601
# 323.15 0.000567
# 293.15 0.0006082 (linear interpolation)
# we have to provide a single value: (values at 273.15 K, 1 bar)
0.000637
